Effects of IL-18 on Nuclear Factor Kappar B and Th2/Th1 Immune Homeotasis in Rat Otitis Media with Effusion

LIU Hua; ZHAO Shouqin; SONG Yang; FAN Erzhong; LI Jie; YANG Lin; GAO Zhan mei

doi:10.3969/j.issn.1672-2922.2013.04.035

Abstract：Objective To investigate the effects of IL-18 on NF-κB and Th2/Th1 immune homeotasis in the middle ear of a rat model of OME. Methods Eighteen Sprague-Dawley (SD) rats were randomly divided into three groups:group A (OME model group, n=12 ears);group B (IL-18 injection group, n=12 ears);and group C (control group, n=12 ears). The rat model of OME was established in groups A and B by sensitization with ovalbumin and later transtympanic challenging. IL-18 (0.2 ml, 1μg) and Saline (0.2 ml) were respectively injected in all groups on days 1, 2, 7, 8, 15 and 16. Morphologic changes of middle ear epithelial cells and inflammatory cells infiltration were evaluated under a microscope. The expression of IFN-γ 、IL-4、NF-κB p65 in temporal bone marrow and middle ear mucosa was evaluated by immunohistochemistry. Results The expression of IFN-γin group B was stronger than that in group A and C (both P<0. 05). As compared to group C, the expression of IL-4 in group A and group B was remarkably stronger (both P<0. 05), while no significant difference was found between groups A and B (P>0. 05). Additionally, there was no significant difference in the Th2/Th1(IL-4/IFN-γ)ratio between groups A group B (P>0. 05). Furthermore, NF-κB p65 expression in temporal bone marrow and middle ear mucosa was different among the three groups, with the highest rate of expression in group B and the lowest in group C (P<0. 05). Conclusion IL-18 plays a dual effect role that increases both Th1 cytokine IFN-γand Th2 cytokine IL-4 production. The underlying mechanism may be explained by the fact that IL-18 promotes the activation of NF-κB in the allergic OME rat model.